The invention involves a process for measuring an electrochemical activity of a layer lying on a melt (molten mass or bath), using an electrochemical sensor which has a measuring cell and a counter electrode.
Furthermore, the invention involves an immersion sensor for measuring an electrochemical activity of a layer lying on a melt, using an electrochemical sensor which is arranged on a support and has an electrochemical measuring cell and a counter electrode.
A process of this type and an immersion sensor of this type are known from Radex-Review, Issue 1, 1990, pages 236-243. A measuring process for measuring electrochemical activities, especially of the oxygen content of slag layers lying on iron melts, is described therein. The measurement is done by a conventional electrochemical sensor, which has a measuring cell with zirconium oxide and magnesium oxide as electrolytes and a counter electrode, arranged in the liquid slag layer. In particular, caused by non-homogenieties in the slag, the contact of the sensor with the material to be measured is not exactly defined, so that the measurement result cannot be reproduced with sufficient accuracy.
A similar sensor is described EP 330 264 A1. This sensor is used to determine the bath surface level, wherein the phase boundary between the metal melt and a slag layer lying on the metal melt is determined. A process for the indirect measurement of electrochemical activities in slags on silver melts is described in EP 0 450 090 B1. In this process, an electrochemical measuring cell is arranged in a silver melt. From the measurement, a conclusion is made about the activity in the slag.